The present invention relates to a high-quality silicon carbide (SiC) epitaxial wafer obtained from the crystal growth of silicon carbide, manufacturing method of such wafer, and semiconductor device formed on this wafer.
Since SiC has various crystal structures, in the epitaxial growth of the SiC {0001} face, SiC having a different crystal structure easily gets mixed -into the epitaxially grown portion.
Further, the flatness of the growth surface will be lost due to step bunching or two-dimensional nucleus formation. Thus, in order to form an epitaxial wafer having a flat and uniform crystal structure, with the conventional epitaxial wafer manufacturing technology, a SiC substrate (off substrate) inclined 3° to 8° in the [11 20] direction of the {0001} face is used, and an epitaxial wafer is formed on such substrate with the chemical vapor deposition method (CVD method) (c.f. Patent Document 1).
[Patent Document 1] U.S. Pat. No. 4,912,064
SiC has crystal defects extending in the {0001} direction and crystal defects extending in a direction perpendicular to the {0001} direction. Thus, when an epitaxial wafer is manufactured based on the technology described in Patent Document 1, since both crystal defects existing in the substrate are propagated to the epitaxially grown portion, it is difficult to reduce the defects in the wafer. This situation is shown in FIG. 1a. 
Further, in the manufacture of a SiC epitaxial wafer, the (0001) Si face is used for epitaxial growth. Nevertheless, as the angle of the off substrate becomes small, during the epitaxial growth of the (0001) Si face, step bunching and two-dimensional nucleus formation will occur and the flatness of the epitaxially grown surface will be lost.